copying data from one array to another array

Question

Array One:

 array1 = [{
        "id": 1,
        "name": "aaaaa",
        "attr": [{"attr_code": "a_id", "value": "5"}]
      },
      {
        "id": 2,
        "name": "bbbbb",
        "attr": [{"attr": "a_id", "value": "4"}]
      }]

Array Two:

array2 = [{
    "id": 4,
    "name": "bef",
  },
  {
    "id": 5,
    "name": "bcd",
  }]

Resulting Array:

 resultingArray =  [{
    "id": 1,
    "name": "aaaaa",
    "attr": [{"attr_code": "a_id", "value": "5"}],
    "a_id" :   {"id": 5, "name": "bcd"}
  },
    {
      "id": 2,
      "name": "bbbbb",
      "attr": [{"attr": "a_id", "value": "4"}],
      "a_id" : {"id": 4, "name": "bef"}
    }]

I am looking to add the array2 objects into array1 based on id's of array2. I have tried using map function on both the arrays to compare and add the object but I didn't succeed. Can you please suggest me how to do it?

Thank you

The posted question does not appear to include any attempt at all to solve the problem. StackOverflow expects you to try to solve your own problem first, as your attempts help us to better understand what you want. Please edit the question to show what you've tried, so as to illustrate a specific problem you're having in a minimal reproducible example. For more information, please see How to Ask and take the tour. — CertainPerformance
– CertainPerformance, Commented Oct 3, 2018 at 4:08

Mohammad Ali Rony · Accepted Answer · 2018-10-03 04:23:38Z

1

Add the array2 objects into array1 based on ids of array2.

let array1 = 
[
  {
    "id": 1,
    "name": "aaaaa",
    "attr": [{"attr_code": "a_id", "value": "5"}]
  },
  {
    "id": 2,
    "name": "bbbbb",
    "attr": [{"attr": "a_id", "value": "4"}]
  }
];
      
let array2 = [{
    "id": 4,
    "name": "bef",
  },
  {
    "id": 5,
    "name": "bcd",
  }
];
 
let resultingArray=[]; 

array1.forEach(function(element) {
  element['a_id'] = [];
  element['attr'].forEach(function(attr) {
        element['a_id'].push(array2.find(function(item) {
        return item.id == attr.value;
      }));
   });
  resultingArray.push(element)
});

console.log(resultingArray);

answered Oct 3, 2018 at 4:23

Mohammad Ali Rony

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Comments

Harshith Rai · Accepted Answer · 2018-10-03 04:26:23Z

I presume you intend to extract the object whose ID is equal to the value field the in the each object in array1.

var array1 = [{
        "id": 1,
        "name": "aaaaa",
        "attr": [{"attr_code": "a_id", "value": "5"}]
      },
      {
        "id": 2,
        "name": "bbbbb",
        "attr": [{"attr": "a_id", "value": "4"}]
      }];

var array2 = [{
    "id": 4,
    "name": "bef",
  },
  {
    "id": 5,
    "name": "bcd",
  }];

var resultingArray = [];
for(var i = 0; i < array1.length; i++) {
    resultingArray[i] = array1[i];
    for(var j = 0; j < array2.length; j++) {
        if(resultingArray[i].attr[0].attr_code.value === array2[j].id) {
            resultingArray[i].push("a_id": array2[j]);
        }
    }
}

You just need to lop through array1, and for each object in array1, you need to find corresponding objects in array2 which match the criterion.

protoproto · Accepted Answer · 2018-10-03 04:26:25Z

0

You can use array map and array index to do:

var array1 = [{
        "id": 1,
        "name": "aaaaa",
        "attr": [{"attr_code": "a_id", "value": "5"}]
      },
      {
        "id": 2,
        "name": "bbbbb",
        "attr": [{"attr": "a_id", "value": "4"}]
      }];
var array2 = [{
    "id": 4,
    "name": "bef",
  },
  {
    "id": 5,
    "name": "bcd",
  }];
var result = array1.map(current=>{
  //find index of attr in array2
  let index = array2.findIndex(c=>{
    if (c['id']===(Number(current['attr'][0]['value'])))
      return c;
  });
  current["a_id"] = array2[index];
  return current;
});
console.log(result);

answered Oct 3, 2018 at 4:26

protoproto

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Comments

Vishu Bhardwaj · Accepted Answer · 2018-10-03 04:30:00Z

Please check if the following code suites your requirement. You may need to make some changes.

function mergeArrays3 (arr1, arr2) {
 return arr1.map((value, index) => {
  let object = null;
  let result = {...value};
  for (let element of arr2) {
   if (element.id == parseInt(value.attr[0].value)) {
    object = element;
    break;
   }
  }
  if (object != null) {
   let attr = value.attr[0];
   if (attr.hasOwnProperty("attr")) {
    result[value.attr[0].attr] = object;
   } else if (attr.hasOwnProperty("attr_code")) {
    result[value.attr[0].attr_code] = object;
   }
  }
  return result;
 });
}

I loop over first array and find an element in second array matching id of value.attr[0].value. If found then i added this object in the first array at key of value.attr[0].attr or value.attr[0].attr_code.

jonathangersam · Accepted Answer · 2018-10-03 05:23:15Z

I have tried using map function on both the arrays to compare and add the object but I didn't succeed

Below is the functional programming approach using map():

/* GIVEN */
const array1 = [{
    "id": 1,
    "name": "aaaaa",
    "attr": [{
      "attr_code": "a_id",
      "value": "5"
    }]
  },
  {
    "id": 2,
    "name": "bbbbb",
    "attr": [{
      "attr": "a_id",
      "value": "4"
    }]
  }
]

const array2 = [{
    "id": 4,
    "name": "bef",
  },
  {
    "id": 5,
    "name": "bcd",
  }]

/* From array2, make an object keyed by the 'id' field. We'll use this as a key-value lookup table  */
const lookupTable = array2.reduce((accum, item) => {
    accum[item.id.toString()] = item
    return accum
  }, {})
  
  
console.log('***LOOKUP TABLE***\n', lookupTable) // result is an object we use to lookup

/* From array1, we append data from the lookup table */
const final = array1.map(item => {
    item.a_id = lookupTable[item.attr[0].value]
    return item
  })

console.log("***RESULT***\n", final)

Hope this helps. Cheers,

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